1. Field of the Invention
The present invention relates to wireless IC devices, and in particular, relates to wireless IC devices such as non-contact wireless IC media and non-contact wireless IC tags used in, for example, Radio Frequency Identification (RFID) systems.
2. Description of the Related Art
To date, various wireless IC devices on which wireless IC chips are mounted have been proposed.
Japanese Unexamined Patent Application Publication No. 2002-298109, for example, discloses a non-contact wireless IC medium produced by the following steps. First, as shown in a cross-sectional view in FIG. 4A, an antenna portion 103 is formed on a separable sheet 101 using conductive paste, conductive ink, or the like, and an IC chip 109 is mounted on the antenna portion 103 so as to be electrically connected to the antenna portion 103. Next, as shown in a cross-sectional view in FIG. 4B, an adhesive sheet 111 is closely adhered to the antenna portion 103 and the IC chip 109. Finally, as shown in a cross-sectional view in FIG. 4C, the separable sheet 101 is stripped off.
The non-contact wireless IC medium is used while the adhesive sheet 111 is adhered to an article and the IC chip 101 is exposed to the outside. Therefore, when the article to which the non-contact wireless IC medium is adhered is brought into contact with other articles, the shock can directly act on the IC chip 109, and the IC chip 109 can be damaged. This can lead to malfunction of the wireless IC medium.